Outputting tcpdump information on the screen

Hello forum, I am attempting to run tcpdump command in the following way:

ofSystem("sudo tcpdump -v wlan0");

I am having trouble however outputting the results using ofDrawBitmapStringHighlight() and drawString().Unix commands like ls usually return one result, but how would I run command like tcpdump that does not exit after it gets executed? Please suggest a way how to display unix commands outputs in the terminal.

Thanks in advance!